Food allergies are immune reactions

Food allergy is a genuine immune response - to be precise, it is an abnormal and excessive immune response produced by the human immune system to food antigens that are not originally pathogenic. It has nothing to do with "delicate gastrointestinal", "getting angry" or "eating a bad stomach".

When I was attending a consultation in the allergy department last week, I met a grandma who brought her 3-year-old grandson. The child had a red rash around his mouth and kept rubbing his eyes. As soon as the grandma came in, she said, "Doctor, please prescribe some antipyretic medicine. This child will get angry after eating too much mango." When I asked about the medical history, I found that I had the same problem last time when I ate Xiaotainong, and I even vomited once. I did a skin prick test and found that the mango-specific IgE was strongly positive. It was clear that I had a food allergy. My grandma still didn't believe it, "Our children were fine eating mangoes before."

To put it bluntly, your body's immune system is looking at the wrong person when it comes to work. Originally, the normal immune system acted as the community's security team. It usually only stopped "suspicious persons" carrying pathogens, such as influenza viruses and E. coli. When it encountered high-quality proteins that came in with food, it would directly let them go. But some people’s immune systems don’t know which link is wrong, and they regard a certain food protein as a bad guy that wants to invade. The first time they encounter it, they remember the characteristics of this “bad guy”. The next time they encounter it, they immediately sound the alarm and mobilize their immune cells to release inflammatory mediators such as histamine and leukotrienes. The symptoms on the body include redness and swelling around the mouth, skin rashes, sneezing and coughing, and even severe laryngeal edema and shock, all of which are the result of an excessive immune response.

As for why a healthy immune system suddenly suffers from "visual decline", there is no unified conclusion in the academic community. Scholars in different research directions have their own evidence. One group supports the "hygiene hypothesis" that has been circulating for many years. They feel that people's lives are too clean now, and they have been exposed to too few microorganisms since childhood. The immune system has never seen a real bad guy, and it will attack randomly when there is nothing to do. You can see that the allergy rate of children who grow up in rural areas is indeed much lower than that in cities. The survey data can completely match it. There is also a school that has become particularly popular in recent years, which believes that the problem lies in the intestinal barrier. Leaky intestines and intestinal flora disorders can cause incompletely digested food proteins to leak into the blood, triggering misjudgments by the immune system. This is also the theoretical basis of many probiotics and hypoallergenic diet plans. However, there is currently not enough large-scale clinical evidence to support the effectiveness of routine supplementation of probiotics for ordinary people with allergies. Other studies have pointed out that immune disorders caused by staying up late, high stress, and short-term infections may also trigger sudden allergic reactions in people who are not allergic. I have met a 28-year-old girl before who never had a problem eating shrimp. After she got COVID-19 last year, she broke out in hives all over her body after eating a bite of shrimp. The IgE was indeed elevated, and she has not recovered yet.

Many people confuse food allergies and food intolerances, but they are not the same thing at all. I have a friend who says he is allergic to milk every time he drinks milk and has diarrhea. However, he went for a negative IgE test and found that drinking lactose-free milk was fine. Typical lactose intolerance means that the body lacks lactase and cannot break down the lactose in milk. The immune system is not involved in the whole process, so it is not considered an allergy at all. Some people think that "my allergy symptoms are mild and it's fine." This is also a misunderstanding. The intensity of the immune response may be different every time. It was just a rash last time, but anaphylactic shock may occur next time. I have seen too many people think that "it was just a little itchy after eating it last time, it was fine" and ended up in the emergency room.

As for whether you should avoid food for the rest of your life after you develop an allergy, there are different clinical approaches. The traditional plan is to strictly avoid allergenic foods and not even touch processed foods containing trace ingredients. This is safe and sound, but it will indeed affect the quality of life. Nowadays, many doctors will perform oral immune tolerance induction under close monitoring for children with milk and egg allergies. They will start to expose the allergenic protein little by little at a small dose to allow the immune system to slowly "recognize" it and stop attacking. Many children can eat normally after half a year to a year. However, this program must not be tried at home, as it may cause serious allergic reactions. And not all allergies can induce tolerance. Most people may have to live with allergies such as peanuts and seafood for a lifetime, so it is safer to strictly avoid them.

After all, there is really no need to demonize food allergies, nor should we take them seriously. The essence is that the immune system is playing a minor joke. If you really suspect that you are allergic, don't blindly search on Baidu and just avoid eating it, and don't force yourself to eat it. Go to the allergy department for a standardized test to find out whether you are allergic, what you are allergic to, and how severe it is. This is better than anything else. Oh, by the way, don’t believe the nonsense that “allergies are for detoxification”. If it’s really serious, it can kill someone.